
#include <limits.h>
#include <stdint.h>
#include <string.h>

#include <sodium/crypto_hash_sha512.h>
#include <sodium/crypto_sign_edwards25519sha512batch.h>
#include <sodium/crypto_verify_32.h>
#include <sodium/private/ed25519_ref10.h>
#include <sodium/randombytes.h>
#include <sodium/utils.h>

int
crypto_sign_edwards25519sha512batch_keypair(unsigned char *pk,
                                            unsigned char *sk)
{
  ge25519_p3 A;

  randombytes_buf(sk, 32);
  crypto_hash_sha512(sk, sk, 32);
  sk[0] &= 248;
  sk[31] &= 127;
  sk[31] |= 64;
  ge25519_scalarmult_base(&A, sk);
  ge25519_p3_tobytes(pk, &A);

  return 0;
}

int
crypto_sign_edwards25519sha512batch(unsigned char *sm,
                                    unsigned long long *smlen_p,
                                    const unsigned char *m,
                                    unsigned long long mlen,
                                    const unsigned char *sk)
{
  crypto_hash_sha512_state hs;
  unsigned char nonce[64];
  unsigned char hram[64];
  unsigned char sig[64];
  ge25519_p3 A;
  ge25519_p3 R;

  crypto_hash_sha512_init(&hs);
  crypto_hash_sha512_update(&hs, sk + 32, 32);
  crypto_hash_sha512_update(&hs, m, mlen);
  crypto_hash_sha512_final(&hs, nonce);
  ge25519_scalarmult_base(&A, sk);
  ge25519_p3_tobytes(sig + 32, &A);
  sc25519_reduce(nonce);
  ge25519_scalarmult_base(&R, nonce);
  ge25519_p3_tobytes(sig, &R);
  crypto_hash_sha512_init(&hs);
  crypto_hash_sha512_update(&hs, sig, 32);
  crypto_hash_sha512_update(&hs, m, mlen);
  crypto_hash_sha512_final(&hs, hram);
  sc25519_reduce(hram);
  sc25519_muladd(sig + 32, hram, nonce, sk);
  sodium_memzero(hram, sizeof hram);
  memmove(sm + 32, m, (size_t)mlen);
  memcpy(sm, sig, 32);
  memcpy(sm + 32 + mlen, sig + 32, 32);
  *smlen_p = mlen + 64U;

  return 0;
}

int
crypto_sign_edwards25519sha512batch_open(unsigned char *m,
                                         unsigned long long *mlen_p,
                                         const unsigned char *sm,
                                         unsigned long long smlen,
                                         const unsigned char *pk)
{
  unsigned char h[64];
  unsigned char t1[32], t2[32];
  unsigned long long mlen;
  ge25519_cached Ai;
  ge25519_p1p1 csa;
  ge25519_p2 cs;
  ge25519_p3 A;
  ge25519_p3 R;
  ge25519_p3 cs3;

  *mlen_p = 0;
  if(smlen < 64
     || smlen - 64 > crypto_sign_edwards25519sha512batch_MESSAGEBYTES_MAX)
  {
    return -1;
  }
  mlen = smlen - 64;
  if(sm[smlen - 1] & 224)
  {
    return -1;
  }
  if(ge25519_has_small_order(pk) != 0
     || ge25519_frombytes_negate_vartime(&A, pk) != 0
     || ge25519_has_small_order(sm) != 0
     || ge25519_frombytes_negate_vartime(&R, sm) != 0)
  {
    return -1;
  }
  ge25519_p3_to_cached(&Ai, &A);
  crypto_hash_sha512(h, sm, mlen + 32);
  sc25519_reduce(h);
  ge25519_scalarmult(&cs3, h, &R);
  ge25519_add(&csa, &cs3, &Ai);
  ge25519_p1p1_to_p2(&cs, &csa);
  ge25519_tobytes(t1, &cs);
  t1[31] ^= 1 << 7;
  ge25519_scalarmult_base(&R, sm + 32 + mlen);
  ge25519_p3_tobytes(t2, &R);
  if(crypto_verify_32(t1, t2) != 0)
  {
    return -1;
  }
  *mlen_p = mlen;
  memmove(m, sm + 32, mlen);

  return 0;
}
